Simultaneous multiple post-labelling delay ASL MRI and [¹⁸F]FDG PET in a mixed memory clinic population and healthy...

Area of Science:

• Neuroimaging
• Medical Physics
• Radiology

Background:

• Arterial spin labelling (ASL) MRI measures cerebral blood flow (CBF).
• Hybrid [18F]FDG PET/MRI allows simultaneous imaging.
• Assessing concordance between ASL and FDG PET is crucial for clinical application in memory disorders.

Purpose of the Study:

• To evaluate the quantitative and visual agreement between multi-PLD ASL MRI CBF and [18F]FDG PET.
• To assess ASL MRI interpretability and concordance in a mixed memory clinic population.

Main Methods:

• Hybrid [18F]FDG PET/MRI with multi-PLD pseudo continuous ASL was performed on 96 memory clinic patients, 38 elderly controls, and 12 young controls.
• ASL image interpretability, concordance with [18F]FDG PET, and Z-score map utility were visually assessed.
• Regional associations between CBF and [18F]FDG uptake ratio (SUVr) were analyzed using regression models.

Main Results:

• ASL CBF maps were uninterpretable or discordant in 53% of patients and 37% of elderly controls.
• Only 14% of patient ASL MRI scans showed concordance with [18F]FDG PET.
• Increased spatial coefficient of variation (sCOV) correlated with disease severity and predicted uninterpretable scans.

Conclusions:

• Multi-PLD ASL provides CBF measurements that correlate with disease severity.
• Poor ASL image quality and low regional concordance with [18F]FDG PET limit its clinical use in memory clinic patients.
• Further optimization of ASL techniques is needed for reliable application in neurodegenerative disease assessment.